4. Stay Engaged

In this economy, the audition doesn't end when you've landed the job. To solidify your standing, be it in a temp job or a long-term position, involve yourself in all aspects of office life, from bringing in bagels to tackling tough tasks. Show your loyalty by arriving on time — or even early — every day, despite the weather. If the company has a volunteer activity, join in. In other words, be a team player. "This is important for the success of every employee, regardless of age," says Hvidding.

If you're lucky enough to have a permanent position, don't feel entitled. Companies value longtime employees' institutional memory, but to be irreplaceable you must stay invested. Take the initiative and assume new responsibilities. Broaden your experience to meet the company's evolving needs, whether that means taking a class or volunteering for a committee. "Well-regarded employees of any age work to keep their skills up-to-date," says Devin Ryder, a senior training and development specialist at Harvard's Center for Workplace Development. Bottom line: The more versatile you are, the more valuable you are.

Also, it's an intergenerational workplace out there. You may report to someone younger than you, or you may be teamed with younger colleagues. Shake off any resistance to new ideas and techniques. "There's little room today for the employee who wants to do things the way they've always been done," says Jackson. Instead of grumbling about what your colleagues don't know, share what you've learned, and be open to learning from them.

Remember: If you don't schmooze, you lose. Used wisely, a bit of chitchat helps create a personal connection with your boss and colleagues. ( Used unwisely, it makes you a pest.) How to go about it? My advice: Keep it light and genuine, and see what develops.

5. Never Discount Your Worth

Several months after I rode the subway with those laid-off Citibank workers, I heard from the man I'd met on the train. He and some of his colleagues had pooled their 401(k)s and started their own company. "We don't have the perks or pay that we used to," he said, "but we own this!" Their first customer? Their former employer, Citibank.

Even if you don't seek to start your own company, you can learn from his example. You have what employers need — even if they don't always realize it. Says Jackson: "A seasoned employee shouldn't underestimate what he or she has to offer." With confidence, networking, and face time, you can show anyone why they need you.

Chris Gardner, author of The Pursuit of Happyness, is AARP's Ambassador for Pursuit and Happyness. Additional reporting by Tina Adler.